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Description and Format of CREX Tables B and D
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Every CREX message that is presented to the CREXLIB software, either for input
(reading/decoding) or output (writing/encoding) purposes,
must have CREX
tables associated with it, which exist as separate ASCII files.
It is extremely important that each of these tables not only be syntactically correct
but also complete, in the sense that it contains all the necessary descriptors needed
for encoding or decoding the CREX message. The WMO version of these tables contain
all the approved CREX descriptors. The user has the choice of using the WMO version
of these tables which contain all the current CREX descriptors and can be downloaded from
"Official Internationally-Coordinated WMO BUFR-CREX Tables",
or using a subset of these tables that consist only of the descriptors that are needed.
The first entry in each record of Table D is a sequence descriptor. It is followed by
the list of descriptors it defines. This list may consist of element descriptors, replication
descriptors, operator descriptors and sequence descriptors. The last descriptor in each
list is followed by the # character which serves as a marker to the CREXLIB software of the
location of the end of the list.